Legally speaking, “25 to life” refers to a prisoner’s life sentence with the possibility of parole after 25 years. By doing this, a definite minimum sentence can be established without fully eliminating the possibility of parole release.
While the official sentence may call for 25 years of incarceration before parole is granted, in some situations this may depend on the conditions of the prison population, a prisoner’s behaviour, or other reasons. However, if parole is refused, the sentence can go on until the inmate dies.
The sentence may simply be referred to as a “life sentence” in cases of especially egregious crimes and forbid the prospect of release.